This invention is related to exhaust systems, and, more particularly, to a muffler which will facilitate exhaust action and noise abatement of high velocity exhaust gas flow. Internal combustion engines and turbines produce exhaust combustion gases and the discharged exhaust is frequently accompanied by undesirable levels of noise. The problem of muffling and evacuating such exhaust gases is well known.
Automobiles utilize exhaust systems coupled with an internal combustion engine which are comprised of combinations of headers, collectors, converters and mufflers. One type of muffler contains a plurality of baffles to provide a plurality of chambers within a casing or housing. The baffles are arranged to form a circuitous path from the inlet end of the housing to its exit end. Typically, sound absorbing material such as stainless steel wool is also provided in portions of the housing to further reduce the high frequency components of noise.
Another type of exhaust system component which facilitates the evacuation of exhaust gases is described in Sung U.S. Pat. No. 5,282,361. Induction and acceleration of air is obtained from forward movement of a vehicle by a guided flow depression device and a forced exhaust device to improve engine operating efficiency by reducing back pressure at engine exhaust ports. However, little or no sound muffling is provided by the device.
It is an object of the present invention to provide a novel muffler which also facilitates extraction of the exhaust from the engine.
Another object is to provide such a muffler with components which can be readily fabricated and assembled to provide a relatively long lived device.
It is also a specific object to provide such a muffler which is relatively low cost, is relatively lightweight, has operating characteristics that can be readily tuned to a particular engine and exhaust system, and is resistant to rust and corrosion.
It has now been found that the foregoing and related objects may be readily attained in a muffler and exhaust extractor comprising an elongated, generally cylindrical casing having inlet and outlet ends in which there is disposed adjacent the inlet end, an elongated generally frustroconical baffle with the smaller diameter portion being spaced from the inlet end. The peripheral wall of the baffle has perforations therein which are closely spaced about the periphery and extend over the major portion of the axial length thereof. The baffle is spaced from the shell over the major portion of its axial length to provide a chamber thereabout.
Also disposed within the chamber is a generally cylindrical baffle having one end extending over the smaller diameter portion of the frustroconical baffle. The peripheral wall of the cylindrical baffle is spaced from the casing over substantially the entire length thereof to provide a chamber thereabout. The peripheral wall has closely spaced perforations extending circumferentially thereabout and over the major portion of its length.
In operation, a substantial portion of the volume of exhaust gases entering the inlet end of the frustroconical baffle exits through the perforations in its peripheral wall and thence move generally axially in the chamber thereabout and into the chamber about the cylindrical baffle. The exhaust gases then pass into the cylindrical baffle through its apertures and move axially therethrough to the exit end of the casing.
The end of the smaller diameter portion of the frustroconical baffle is open so that some of the exhaust gases are accelerated and pass axially therethrough directly into the interior of the cylindrical baffle.
Desirably, the apertures in the peripheral wall of the cylindrical baffle are oriented in a spiral pattern and are provided by punching and deforming the wall to provide louvers or internally extending scoop-shaped formations opening towards the exit end.
Desirably, the inlet end of the frustroconical baffle is supported by a first end cap with an outwardly extending generally cylindrical flange for connection to an element of the exhaust system. The inlet end of the casing is secured to the outer surface of the first end cap. The inlet end of the cylindrical baffle is supported by the outlet end of the frustroconical baffle and the outlet end of the cylindrical baffle is supported by a removable second or outlet end cap in the casing adjacent the outlet end thereof.
In another embodiment, the smaller diameter end portion of the frustroconical baffle is closed and all exhaust gases must exit through the apertures in the peripheral wall of the frustroconical baffle and pass into the cylindrical baffle through the apertures in its peripheral wall.
If so desired, sound dampening, heat resistant fibrous material such as fiberglass can be inserted into the chamber about the baffles.